1 files changed, 149 insertions, 0 deletions
diff --git a/src/pkg/runtime/cgo/darwin_386.c b/src/pkg/runtime/cgo/darwin_386.c
new file mode 100644
index 000000000..6d4e259be
--- /dev/null
+++ b/src/pkg/runtime/cgo/darwin_386.c
@@ -0,0 +1,149 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include <pthread.h>
+#include "libcgo.h"
+
+static void* threadentry(void*);
+static pthread_key_t k1, k2;
+
+#define magic1 (0x23581321U)
+
+static void
+inittls(void)
+{
+	uint32 x, y;
+	pthread_key_t tofree[128], k;
+	int i, ntofree;
+	int havek1, havek2;
+
+	/*
+	 * Allocate thread-local storage slots for m, g.
+	 * The key numbers start at 0x100, and we expect to be
+	 * one of the early calls to pthread_key_create, so we
+	 * should be able to get pretty low numbers.
+	 *
+	 * In Darwin/386 pthreads, %gs points at the thread
+	 * structure, and each key is an index into the thread-local
+	 * storage array that begins at offset 0x48 within in that structure.
+	 * It may happen that we are not quite the first function to try
+	 * to allocate thread-local storage keys, so instead of depending
+	 * on getting 0x100 and 0x101, we try for 0x108 and 0x109,
+	 * allocating keys until we get the ones we want and then freeing
+	 * the ones we didn't want.
+	 *
+	 * Thus the final offsets to use in %gs references are
+	 * 0x48+4*0x108 = 0x468 and 0x48+4*0x109 = 0x46c.
+	 *
+	 * The linker and runtime hard-code these constant offsets
+	 * from %gs where we expect to find m and g.
+	 * Known to ../cmd/8l/obj.c:/468
+	 * and to ../pkg/runtime/darwin/386/sys.s:/468
+	 *
+	 * This is truly disgusting and a bit fragile, but taking care
+	 * of it here protects the rest of the system from damage.
+	 * The alternative would be to use a global variable that
+	 * held the offset and refer to that variable each time we
+	 * need a %gs variable (m or g).  That approach would
+	 * require an extra instruction and memory reference in
+	 * every stack growth prolog and would also require
+	 * rewriting the code that 8c generates for extern registers.
+	 *
+	 * Things get more disgusting on OS X 10.7 Lion.
+	 * The 0x48 base mentioned above is the offset of the tsd
+	 * array within the per-thread structure on Leopard and Snow Leopard.
+	 * On Lion, the base moved a little, so while the math above
+	 * still applies, the base is different.  Thus, we cannot
+	 * look for specific key values if we want to build binaries
+	 * that run on both systems.  Instead, forget about the
+	 * specific key values and just allocate and initialize per-thread
+	 * storage until we find a key that writes to the memory location
+	 * we want.  Then keep that key.
+	 */
+	havek1 = 0;
+	havek2 = 0;
+	ntofree = 0;
+	while(!havek1 || !havek2) {
+		if(pthread_key_create(&k, nil) < 0) {
+			fprintf(stderr, "runtime/cgo: pthread_key_create failed\n");
+			abort();
+		}
+		pthread_setspecific(k, (void*)magic1);
+		asm volatile("movl %%gs:0x468, %0" : "=r"(x));
+		asm volatile("movl %%gs:0x46c, %0" : "=r"(y));
+		if(x == magic1) {
+			havek1 = 1;
+			k1 = k;
+		} else if(y == magic1) {
+			havek2 = 1;
+			k2 = k;
+		} else {
+			if(ntofree >= nelem(tofree)) {
+				fprintf(stderr, "runtime/cgo: could not obtain pthread_keys\n");
+				fprintf(stderr, "\ttried");
+				for(i=0; i<ntofree; i++)
+					fprintf(stderr, " %#x", (unsigned)tofree[i]);
+				fprintf(stderr, "\n");
+				abort();
+			}
+			tofree[ntofree++] = k;
+		}
+		pthread_setspecific(k, 0);
+	}
+
+	/*
+	 * We got the keys we wanted.  Free the others.
+	 */
+	for(i=0; i<ntofree; i++)
+		pthread_key_delete(tofree[i]);
+}
+
+static void
+xinitcgo(void)
+{
+	inittls();
+}
+
+void (*initcgo)(void) = xinitcgo;
+
+void
+libcgo_sys_thread_start(ThreadStart *ts)
+{
+	pthread_attr_t attr;
+	pthread_t p;
+	size_t size;
+	int err;
+
+	pthread_attr_init(&attr);
+	pthread_attr_getstacksize(&attr, &size);
+	ts->g->stackguard = size;
+	err = pthread_create(&p, &attr, threadentry, ts);
+	if (err != 0) {
+		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
+		abort();
+	}
+}
+
+static void*
+threadentry(void *v)
+{
+	ThreadStart ts;
+
+	ts = *(ThreadStart*)v;
+	free(v);
+
+	ts.g->stackbase = (uintptr)&ts;
+
+	/*
+	 * libcgo_sys_thread_start set stackguard to stack size;
+	 * change to actual guard pointer.
+	 */
+	ts.g->stackguard = (uintptr)&ts - ts.g->stackguard + 4096;
+
+	pthread_setspecific(k1, (void*)ts.g);
+	pthread_setspecific(k2, (void*)ts.m);
+
+	crosscall_386(ts.fn);
+	return nil;
+}